diff --git a/src/librustdoc/html/static/css/rustdoc.css b/src/librustdoc/html/static/css/rustdoc.css
index 38e67c233d698..19ff2342b30b1 100644
--- a/src/librustdoc/html/static/css/rustdoc.css
+++ b/src/librustdoc/html/static/css/rustdoc.css
@@ -110,6 +110,7 @@ body {
 	/* Then override it with `anywhere`, which is required to make non-Safari browsers break
 	   more aggressively when we want them to. */
 	overflow-wrap: anywhere;
+	height: 100vh;
 
 	-webkit-font-feature-settings: "kern", "liga";
 	-moz-font-feature-settings: "kern", "liga";
@@ -271,6 +272,14 @@ main {
 	flex-grow: 1;
 	padding: 10px 15px 40px 45px;
 	min-width: 0;
+
+	/* main is the big scrollable element in our documents, insted of body.
+   * To make sure scrolling with spacebar and PageDown works, we initially
+   * focus it using JS. To avoid an outline indicating that focus, we set
+   * outline to none. */
+	height: 100vh;
+	overflow-y: scroll;
+	outline: none;
 }
 
 .source main {
@@ -1767,8 +1776,6 @@ details.rustdoc-toggle[open] > summary.hideme::after {
 	}
 
 	.sidebar {
-		position: fixed;
-		top: 45px;
 		/* Hide the sidebar offscreen while not in use. Doing this instead of display: none means
 		   the sidebar stays visible for screen readers, which is useful for navigation. */
 		left: -1000px;
diff --git a/src/librustdoc/html/static/js/main.js b/src/librustdoc/html/static/js/main.js
index 454c7f557b9bc..bcfcfc82a14bf 100644
--- a/src/librustdoc/html/static/js/main.js
+++ b/src/librustdoc/html/static/js/main.js
@@ -927,6 +927,11 @@ function loadCss(cssFileName) {
     onHashChange(null);
     window.addEventListener("hashchange", onHashChange);
     searchState.setup();
+
+    // In our documents, `main` is the scrollable element instead of body.
+    // To make sure scrolling with spacebar and Page Down works, we initially
+    // focus it.
+    document.getElementsByTagName("main")[0].focus()
 }());
 
 (function () {
diff --git a/src/librustdoc/html/templates/page.html b/src/librustdoc/html/templates/page.html
index cd672aadd7e93..21211f8ea5da1 100644
--- a/src/librustdoc/html/templates/page.html
+++ b/src/librustdoc/html/templates/page.html
@@ -97,7 +97,7 @@ <h2 class="location"></h2>
         </a> {#- -#}
         {{- sidebar|safe -}}
     </nav> {#- -#}
-    <main> {#- -#}
+    <main tabindex="0"> {#- -#}
         <div class="width-limiter"> {#- -#}
             <div class="sub-container"> {#- -#}
                 <a class="sub-logo-container" href="{{page.root_path|safe}}{{krate_with_trailing_slash|safe}}index.html"> {#- -#}